1. Field of the Invention
The present invention relates to a process and apparatus for cleaning vegetables prior to further processing. More particularly, it relates to removing the decayed portions of the exterior of a potato prior to steam or lye peeling of said potato.
2. Description of the Prior Art
Potato processing has become a major industry in the United States and a significant portion of the nation's potato crop now undergoes some form of preparation before being marketed. Frozen potatoes, potato chips and mashed potato flakes are typical of the products prepared from raw whole potatoes. For each of these products, it is necessary that the potato be peeled and blemished portions of the potato flesh be removed prior to processing.
The term blemish is used by the U.S. Department of Agriculture in grading the quality of processed potatoes and includes all defects which detract from the appearance of the final processed potato. A greater number of blemishes found in a given quantity of processed potatoes leads to a lower quality grade for the associated batch of potatoes. Several types of blemishes occur naturally during the growth of potatoes. These include "sunburn" which is a green discoloration resulting from exposure of the potato to sun during growth, "hollow heart" which is a hollow core resulting from overwatering, "scabbing" which is a thickening of the skin resulting from disease of freezing, and insect damage which often results in rot or decay. The terms rot and decay both denote a breakdown of the tissue of the potato and will be used interchangeably hereinafter.
The majority of blemishes found on harvested potatoes result not from natural growth patterns, but rather from bruises which are caused by mechanical impact during harvesting. Initially, such bruises are merely a discoloration located at the peel or skin. With time, however, enzymes released by broken cells cause increasingly greater portions of the potato flesh to rot and turn brown. If the potato peel is breached and bacteria enter, a bacterial rot is caused rather than enzymic rot. In either event, large portions of the potato are blemished as a result of decay.
Peeling during potato processing is presently accomplished by one of two methods. Most commonly, the potatoes are treated with a lye solution which raises the skin from the flesh. Alternatively, the potato may be subjected to a blast of pressurized or superheated steam which has the same effect. After either peeling process, the skin may be washed away using a water stream and abrasive rollers, but such scrubbing leaves the blemished areas of the potato intact. Such a skin removal device is disclosed in U.S. Pat. No. 2,776,690 to Warren.
The method of skin removal described by Warren has little effect on blemishes which extend beneath the potato skin. It is therefore necessary to manually cut away the blemished portions from the peeled potato, a tedious and expensive processing step. Another disadvantage of manual trimming is that the trimmers often removes good flesh from the potato since it is difficult to judge the depth of blemish beneath the surface.
The majority of blemishes which must be removed are rotten or decayed portions of the potato peel and the potato flesh extending inward from the peel. It is desirable, therefore, to provide a method and an apparatus to mechanically remove decayed portions from whole potatoes while removing little or no undecayed potato flesh.